1. Technical Field
The invention relates generally to optical modules, and more particularly to a lens module.
2. Description of Related Art
Currently, along with the development of electronic devices with multiple functions, image pick-up apparatuses have become widely used in a variety of consumer electronic devices, such as notebook computers, personal digital assistants (PDAs), cellular telephones, etc. In the meantime, there is an increasingly demand for improving image quality, which is essentially depended on the quality of a lens module of the image pick-up apparatus. That is, it is a need for developing lens modules with high image quality.
Referring to FIG. 3, a typical lens module 200 includes a barrel 221, a first lens 222, a spacer 223 and a second lens 224. The first lens 222, the spacer 223, and the second lens 224 are accommodated in the barrel 221 sequentially. In addition, the first lens 222, the spacer 223, and the second lens 224 are assembled along an axis direction of the barrel 221 in order to perform optical function. Particularly, such optical elements 222, 223, 224 are put into the barrel 221 in a direction parallel to the optical axis of the lens module 200. Thus, the first lens 222 and the second lens 224 can be maintained in the barrel 221 by way of allowing lateral sides of the lenses 222, 224 to abut against an inside wall of the barrel 221.
In such case, in order to ensure that the lenses 222, 224 can be precisely and firmly mounted inside the barrel 221, the lenses 222, 224 must be precisely manufactured with the external diameter thereof substantially equal to the inner diameter of the barrel 221. However, the equal diameters cause friction between the lateral sides of the lenses 222, 224 and the inside wall of the barrel 221. Therefore, it is understood that the friction makes it difficult to assembling the lenses 222, 224 with the barrel 221. Accordingly, the lenses 222, 224 may be placed improperly in the barrel 221, e.g. not straightly. As a result, the assembling efficiency is lowered and the image quality of the yielded lens module 200 is unsatisfactory. Furthermore, yield for lens module 200 is reduced and cost for that is raised.
What is needed, therefore, is a lens module having improved efficiency on assembling and improved performance on optical quality.